Two blocks of masses m 1 = 2.35 kg and m 2 = 4.70 kg are each released from rest

Question

Two blocks of masses m1 = 2.35 kg and m2 = 4.70 kg are each released from rest at a height of h = 5.50 m on a frictionless track, as shown in the figure below, and undergo an elastic head-on collision. (Let the positive direction point to the right. Indicate the direction with the sign of your answer.)

Determine the velocity of each block just before the collision.

V1i=

V2i=

The answers I got for V1 = -6.9, and for V2 = 13.6, but everytime I type in those answers web assign keeps telling me "your answer has the wrong sign" but when I change it from a negative to a positive and vice versa, it tells me the answer is incorrect.

Explanation / Answer

m1 = 2.35 kg
m2 = 4.70 kg
h = 5.50 m

Initial Potential Energy = Final Kinetic Energy
m1*g*h = 1/2*m1*v1^2
9.8*5.5 = 1/2*v1^2
v1 = 10.38 m/s

Since the track is Frictionless, Therefore both the masses will have same magnitude of velocity, only the direction will be opposite.

Velocity of each block just before the collision.

V1i = 10.38 m/s
V2i = - 10.38 m/s

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